Age-Related Macular Degeneration (AMD)

Definition

Age-related macular degeneration (AMD) is a common eye condition among people aged 50 and older. It causes damage to the macula, the small central area of the retina responsible for central vision, leading to vision loss in the centre of the visual field.

Aetiology

AMD is primarily caused by ageing and genetic factors, but other contributing factors include:

Environmental influences such as exposure to UV light
Smoking
Poor diet
High blood pressure
Obesity

Pathophysiology

AMD involves the deterioration of the macula. There are two main types of AMD:

Dry AMD: Characterised by the thinning of the macula and the presence of drusen (small yellow deposits).
Wet AMD: Involves the growth of abnormal blood vessels under the retina that can leak fluid or blood, leading to rapid vision loss.

Risk Factors

Age (most common in individuals over 50)
Family history of AMD
Smoking
High blood pressure
Obesity
Poor diet lacking in fruits and vegetables
High exposure to UV light
Cardiovascular disease
Being of Caucasian ethnicity
Female gender

Signs and Symptoms

Common signs and symptoms of AMD include:

Blurred or reduced central vision
Visual distortions, such as straight lines appearing wavy
Difficulty recognising faces
Need for brighter light when reading or doing close work
Increased difficulty adapting to low light levels
Decreased colour perception
Visual hallucinations (Charles Bonnet syndrome)

Investigations

Clinical history and physical examination
Visual acuity test
Fundus examination using a slit-lamp microscope
Ocular coherence tomography (OCT) to assess the macula
Fluorescein angiography if wet AMD is suspected
Amsler grid test to detect visual distortions

Management

Primary Care Management

Referral to an ophthalmologist: For further evaluation and management
Patient education: On the importance of smoking cessation, balanced diet, and UV protection

Specialist Management

Dry AMD: Management focuses on lifestyle modifications and monitoring. Use of antioxidant vitamins and zinc supplements as recommended by the AREDS study.
Wet AMD: Intravitreal injections of anti-VEGF (vascular endothelial growth factor) agents such as ranibizumab or aflibercept to inhibit abnormal blood vessel growth
Laser therapy in specific cases to destroy abnormal blood vessels
Low vision aids and rehabilitation
Regular follow-up to monitor disease progression

References

Patient.info. (2024). Age-related Macular Degeneration. Retrieved from Patient.info
NHS. (2023). Age-related Macular Degeneration. Retrieved from NHS
British Medical Journal (BMJ). (2022). Age-related Macular Degeneration: Diagnosis and Management. Retrieved from BMJ
American Academy of Ophthalmology (AAO). (2021). Clinical Practice Guidelines: Age-related Macular Degeneration. Retrieved from AAO